d3.interpolate() Function

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The Interpolate() function in D3.js is used to interpolate the two given values. In the case of colors, it is used to form a third color from the given two colors.

Syntax:

d3.interpolate(a, b);

Parameters: This function accepts two parameters as mentioned above and describe below.

a: It is an arbitrary value.
b: It is an arbitrary value.

Return Values: It returns a function.

Example 1: When colors are given as a parameter.

HTML

<!DOCTYPE html> 
<html lang="en"> 
  
<head> 
    <meta charset="UTF-8"> 
    <meta name="viewport" content= 
        "width=device-width, initial-scale=1.0"> 
</head> 
  
<body> 
    <!--fetching from CDN of D3.js -->
    <script type="text/javascript" 
        src="https://d3js.org/d3.v4.min.js"> 
    </script> 
      
    <script> 
        let intr = d3.interpolate("red", "green") 
        console.log("Type of returned function is: ", 
                typeof (intr)); 
        console.log(intr(0.1)) 
        console.log(intr(1)) 
        console.log(intr(0.4)) 
    </script> 
</body> 
  
</html> 

Output:

Example 2: When number is given as a parameter.

HTML

<!DOCTYPE html> 
<html lang="en"> 
  
<head> 
    <meta charset="UTF-8"> 
    <meta name="viewport" content= 
        "width=device-width, initial-scale=1.0"> 
</head> 
  
<body> 
    <!--fetching from CDN of D3.js -->
    <script type="text/javascript" 
        src="https://d3js.org/d3.v4.min.js"> 
    </script> 
      
    <script> 
        let intr = d3.interpolate(41, 550) 
        console.log("Type of returned function is: ", 
                typeof (intr)); 
        console.log(intr(0.2)) 
        console.log(intr(0.3)) 
        console.log(intr(0.4)) 
    </script> 
</body> 
  
</html> 

Output:

Example 3: When an array is given as parameter:

HTML

<!DOCTYPE html> 
<html lang="en"> 
  
<head> 
    <meta charset="UTF-8"> 
    <meta name="viewport" content= 
        "width=device-width, initial-scale=1.0"> 
</head> 
  
<body> 
    <!--fetching from CDN of D3.js -->
    <script type="text/javascript" 
        src="https://d3js.org/d3.v4.min.js"> 
    </script> 
      
    <script> 
        let intr = d3.interpolate( 
            [19, 33, 2], [1, 12, 10]) 
        console.log("Type of returned function is: ", 
                typeof (intr)); 
                  
        console.log(intr(0.1)) 
        console.log(intr(1)) 
        console.log(intr(0.4)) 
    </script> 
</body> 
  
</html> 